According to the National Cancer Institute, lung cancer is the leading cause of cancer death (hypertext transfer protocol://www.cancer.gov/cancertopics/types/lung). In 2008, approximately 215,000 new lung cancer patients were diagnosed in the United States alone. Roughly 87% of these patients will have on-small cell lung cancer (NSCLC).
Smoking, particularly of cigarettes, is by far the main contributor to lung cancer. In the U.S., it is estimated that there are 45 million current and 45 million former smokers at risk for developing lung carcinoma. Lung cancer is estimated to remain a major health problem for at least the next 50 years.
Over 75% of lung cancer cases are diagnosed in late stages because there remains no practical way to screen the large numbers of people at risk. Early detection offers the promise of improved cure rates.
Attempts have been made to identify and stratify individuals at high risk for developing lung cancer and early detection. Initially spectum cytology and chest X-ray were used as screening tools. Unfortunately these procedures failed to increase the number of curable cases.
These procedures were supplanted by computerized tomography (CT) scans, which are more sensitive than chest X-ray. Unfortunately, broad application of CT screening of the at risk population has several drawbacks including high false positives (detection of benign lung nodules) and poor ability to identify central tumors. Because of the high false positive rate, approaching 50%, it is estimated that for every lung cancer death prevented by CT screening, two unnecessary invasive procedures will be conducted.
As such, a need exists for methods useful for detecting lung cancer, and in particular biomarkers that can detect early stages of the disease and are largely non-invasive.